The present disclosure relates to development devices that supply toner to an image carrier and electrophotographic image forming apparatuses including the development device.
An electrophotographic image forming apparatus forms an electrostatic latent image by irradiating a circumferential surface of an image carrier (photosensitive drum) with light based on image information read from an original image or image information obtained, by transmission and so on, from an outer device such as a computer. The image forming apparatus supplies toner from the development device to the electrostatic latent image and forms a toner image, and then transfers the toner image onto paper. After the transfer processing, fusing processing is performed on the toner image, and then the paper is ejected externally.
The following describes a development method using a dry toner in an image forming apparatus using an electrophotographic process. For the development method, a two component developer is used. The two component developer includes a magnetic carrier and toner. A magnetic roller (toner supply roller) and a development roller are used. The magnetic roller carries the developer. The development roller only carries toner. In transitioning the toner onto the development roller using the magnetic roller, a toner thin layer is formed by transitioning only non-magnetic toner onto the development roller, with the magnetic carrier remaining on the magnetic roller. The development roller is disposed so as not to have contact with the photosensitive drum. In an opposite area (development area) where the development roller and the photosensitive drum are opposing each other, the toner is attached to the electrostatic latent image on the photosensitive drum by alternating electric field.
In recent years, in the image forming apparatus, an apparatus configuration has become more complicated along with progress in color printing and high-speed processing. In addition, to respond to high-speed processing, high rotation of a toner stirring member within the development device is required. Especially, according to the development method as described above, in an opposite area where the development roller and the magnetic roller are opposing each other, a magnetic brush formed on the magnetic roller causes only the toner to be carried by the development roller. Furthermore, the toner that has not been used for the development is taken off the development roller. This is likely to cause the toner to float in the vicinity of the opposite area where the development roller and the magnetic roller are opposing each other. In some cases, such floating toner accumulates in a periphery of an ear-cutting blade (restricting blade). The accumulated toner, which clumps tighter and adheres to the development roller, is likely to cause an image defect due to toner drop.
To solve such problems, a certain image forming apparatus includes a wall. The wall is provided between the restricting blade and the development area, and is opposing the development roller. In the wall, a flexible sheet member and an elliptical roller are provided. The sheet member forms a part of an internal surface of the wall and is also capable of swinging in a direction perpendicular to the internal surface of the wall. The elliptical roller swings the sheet member.
In addition, a certain development device includes an excitation mechanism. The excitation mechanism provides acceleration to the toner. The direction of the acceleration is a direction in which the toner adhering to a wall of the development device is shaken off into the case.
Furthermore, a certain image forming apparatus oscillates a drive motor itself. The drive motor drives a flow means. The flow means causes the toner in the toner case to flow. The development device prevents toner from remaining on the internal surface of the wall in the toner case by transmitting the oscillation of the drive motor to the toner case.